In-plane switching LCD panel

ABSTRACT

An IPS-LCD panel includes first and second substrates, and a liquid crystal interposed therebetween. The first substrate includes common and pixel electrodes that are formed of a transparent conductive material. Because the common and pixel electrodes are transparent, aperture ratios of the inventive IPS-LCD panel are increased.  
     Another IPS-LCD panel includes opaque pixel electrodes and transparent common electrodes. In forming the opaque pixel electrodes, a black matrix of the same material as the pixel electrodes is also formed on the first substrate. Because the inventive black matrix is much smaller than a conventional one, the aperture ratios of the second inventive IPS-LCD panel become higher.

[0001] This application claims the benefit of Korean Patent ApplicationNo. 1999-58108, filed on Dec. 16, 1999, which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal display device,and more particularly to a liquid crystal display device implementingin-plane switching (IPS) where an electric field to be applied to liquidcrystal is generated in a plane parallel to a substrate.

[0004] 2. Discussion of the Related Art

[0005] Recently, liquid crystal display (LCD) devices with light, thin,and low power consumption characteristics are used in office automationequipment and video units and the like. Driving methods for such LCDstypically include a twisted nematic (TN) mode and a super twistednematic (STN) mode. Although TN-LCDs and STN-LCDs have been put topractical use, they have a drawback in that they have a very narrowviewing angle. In order to solve the problem of narrow viewing angle,IPS-LCD devices have been proposed. IPS-LCD devices typically include alower substrate where a pixel electrode and a common electrode aredisposed, an upper substrate having no electrode, and a liquid crystalinterposed between the upper and lower substrates.

[0006]FIG. 1 is a cross-sectional view illustrating a conventionalTN-LCD panel. As shown in FIG. 1, the liquid crystal display panel haslower and upper substrates 1 a and 1 b with a liquid crystal layer(“LC”) interposed between the lower and upper substrates 1 a and 1 b.The lower substrate 1 a has a thin film transistor (“TFT”) as aswitching element for changing orientation of the LC molecules. The TFTincludes a pixel electrode 15 to apply a voltage to the LC layeraccording to signals from the TFT. The upper substrate 1 b has a colorfilter 25 for implementing colors. There is a common electrode 14 on thecolor filter 25. The common electrode 14 serves as an electrode forapplying a voltage to the LC layer. The pixel electrode 15 is arrangedover a pixel portion “P”, i.e., a display area. Further, to preventleakage of the liquid crystal injected into the space between the twosubstrates 1 a and 1 b, the two substrates 1 a and 1 b are sealed by asealant 6.

[0007] As described above, because the pixel and common electrodes 15and 14 of the conventional TN-LCD panel are positioned on the lower andupper substrates 1 a and 1 b, respectively, the electric field inducedtherebetween is perpendicular to the lower and upper substrates 1 a and1 b. Therefore, unlike the TN or STN-LCD panel, the IPS-LCD panelimplements an electric field parallel to the substrates. A detailedexplanation about operation modes of a typical IPS-LCD panel will beprovided referring to FIGS. 2 to 6.

[0008] As shown in FIG. 2, lower and upper substrates 1 a and 1 b arespaced apart from each other, and a liquid crystal is interposedtherebetween. The lower and upper substrates are called array and colorfilter substrates, respectively. Pixel and common electrodes 15 and 14are disposed on the lower substrate 1 a. The pixel and common electrodes15 and 14 are parallel with and spaced apart from each other. A colorfilter 25 is disposed on a surface of the upper substrate 1 b andopposes the lower substrate 1 a. The pixel and common electrodes 15 and14 apply an electric field “E” to the liquid crystal. The liquid crystalhas a negative dielectric anisotropy, and thus it is aligned parallelwith the electric field “E”.

[0009] FIGS. 3 to 6 conceptually illustrate operation modes of aconventional IPS-LCD device. When there is no electric field between thepixel and the common electrodes 15 and 14, the long axes of the liquidcrystal molecules maintain an angle from a line perpendicular to theparallel pixel and common electrodes 15 and 14. Herein, the angle is 45degrees, for example.

[0010] On the contrary, when there is an electric field between thepixel and common electrodes 15 and 14, there is an in-plane electricfield “E” parallel to the surface of the lower substrate 1 a between thepixel and common electrodes 15 and 14. The in-plane electric field “E”is parallel to the surface of the lower substrate 1 a because the pixeland common electrodes are formed on the lower substrate 1 a.Accordingly, the liquid crystal molecules are twisted so as to align thelong axes thereof with the direction of the electric field, thereby theliquid crystal molecules are aligned such that the long axes thereof areparallel with the line perpendicular to the pixel and common electrodes15 and 14.

[0011] By the above-mentioned operation modes and with additional partssuch as polarizers and alignment layers, the IPS-LCD device displaysimages. The IPS-LCD device has wide viewing angle and low colordispersion. The fabricating processes of this IPS-LCD device are simplerthat other various LCD devices. But, because the pixel and commonelectrodes are disposed on the same plane of the lower substrate, thetransmittance and aperture ratio are low.

[0012] For the sake of discussing the above-mentioned problem of theIPS-LCD device in detail, with reference to FIGS. 7A and 7B, the basicstructure of the IPS-LCD device will be described in detail.

[0013]FIG. 7A is a plan view illustrating in detail the structure of onepixel region in the IPS-LCD device, specifically, a unit pixel region10. In addition, a cross-sectional view taken along a line “B-B” in FIG.7A is illustrated in FIG. 7B.

[0014] On the surface of the transparent substrate 1A adjacent to theliquid crystal layer, a scan signal line 2 made of, for example,aluminum (Al) is formed extending along the x-direction, as shown inFIG. 7A. In addition, a reference signal line 4, also known as a commonline, is formed extending along the x-direction, close to the scansignal line 2 on the +y-direction side thereof. The reference signalline 4 is also made of, for example, Al. A region surrounded by the scansignal line 2, the reference signal line 4, and the video signal lines 3constitutes a pixel region 10, as previously described.

[0015] In addition, the pixel region 10 includes a reference electrode14 formed by the reference signal line 4, and another referenceelectrode 14 formed adjacent to the scan signal line 2. The pair ofhorizontally extending reference electrodes 14 are positioned adjacentto one of a pair of video signal line 3 (on the right side of thefigure), and are electrically connected to each other through aconductive layer 14A which is formed simultaneously with the referenceelectrodes 14.

[0016] In the structure described above, the reference electrodes 14form a pair extending in the direction parallel to the scan signal line2. Stated another way, the reference electrodes form a strip extendingin a direction perpendicular to the video signal lines 3, laterdescribed.

[0017] A first insulating film 11 (see FIG. 7B) made of, for example,silicon nitride is formed on the surface of the lower substrate 1A onwhich the scan signal lines 2 are formed, overlying the scan signal line2, the reference signal lines 4, and the reference electrodes 14. Thefirst insulating film 11 functions as (i) an inter-layer insulating filmfor insulating the scan signal line 2 and the reference signal line 4from the video signal lines 3, (ii) as a gate-insulating layer for aregion in which a thin film transistor (TFT) is formed, and (iii) as adielectric film for a region in which a capacitor Cstg is formed. TheTFT includes a drain electrode 3A and a source electrode 15A. Asemiconductor layer 12 for the TFT is formed near a cross point of thegate and data lines 2 and 3. A first polarization layer 18 is formed onthe other surface of the lower substrate 1A.

[0018] On the first insulating film 11, a display electrode 15 is formedparallel with the reference electrode 14. One end portion of the displayelectrode 15 is electrically connected with the conductive layer 14A,and the other end portion thereof is electrically connected with thesource electrode 15A. Still on the first insulating film 11, a firstplanar film 16 is formed to cover the display electrode 15. A firstalignment film 17 is formed on the first planar film 16.

[0019]FIG. 7B illustrates a cross-sectional view of the upper substrate1B on which a black matrix 300 is formed. A color filter 25 is formed toclose an opening in the black matrix 300. Then, a second planar film 27is formed to cover the color filter 25 and the black matrix 300. Asecond alignment layer 28 is formed on the surface of the second planarfilm 27 facing the liquid crystal layer.

[0020] The color filter 25 is formed to define three sub-pixel regionsadjacent to and extending along the video signal line 3 and to positiona red (R) filter, a green (G) filter, and a blue (B) filter, forexample, from the top of the three sub-pixel regions. The threesub-pixel regions constitute one pixel region for color display.

[0021] A second polarization layer 29 is also arranged on the surface ofthe upper substrate 1B that is opposite to the surface of the uppersubstrate 1B adjacent to the liquid crystal layer, on which variousfilms are formed as described above.

[0022] It will be understood that in FIG. 7B, a voltage applied betweenthe reference electrodes 14 and the display electrode 15 causes anelectric field E to be generated in the liquid crystal layer LC inparallel with the respective surfaces of the lower and upper substrates1A, 1B. This is why the illustrated structure is referred to as the inplane switching, as mentioned above.

[0023] To improve the aperture ratio, the distance between the referenceand display electrodes 14 and 15 should be enlarged. In that case, adriving voltage to induce the electric field between the reference anddisplay electrodes 14 and 15 must be increased to maintain a normaldisplay.

[0024] Further, since the low aperture ratio results in a low brightnessquality of the liquid crystal display device, the incident light fromthe back-light device must be brighter to compensate, which increasespower consumption of the liquid crystal display device.

[0025]FIG. 8 shows an array substrate of another conventional IPS-LCDdevice.

[0026] As shown in FIG. 8, gate and common lines 50 and 54 are arrangedtransversely and parallel with each other. A data line 60 is arrangedperpendicular to the gate and common lines 50 and 54. Gate electrode 52and source electrode 62 are positioned near a cross point of the gateand data lines 50 and 60, and communicate with the gate line 50 and thedata line 60, respectively. Herein, the source electrode 62 overlaps aportion of the gate electrode 52.

[0027] A plurality of common electrodes 54 a are positioned spaced apartand perpendicular to the common line 54. The common electrodes 54 acommunicate with the common line 54. A first connecting line 66communicates with the drain electrode 64, and a plurality of pixelelectrodes 66 a are positioned perpendicular to the first connectingline 66. First ends of the pixel electrodes 66 a communicate with thefirst connecting line 66, and the second ends of pixel electrodes 66 acommunicate with a second connecting line 68 that is positioned over thecommon line 54. Accordingly, the common electrodes 54 a and the pixelelectrodes 66 a are parallel with and spaced apart from each other in analternating pattern.

[0028] Similarly to the array substrate of FIG. 7A, since the pixel andcommon electrodes 66 a and 54 a are formed on the same substrate, theaperture ratio is reduced. That is to say, the opaque pixel and commonelectrodes prevent incident light produced by a back light (not shown)from passing through pixel areas covered by the pixel and commonelectrodes. If distances between the common and pixel electrodes areenlarged to improve the aperture ratios, much stronger driving voltagemust be generated between the electrodes to compensate for the loss ofthe electric fields due to the greater distance therebetween.

[0029] In addition, the intensity of the back light must be increased tocompensate for the loss of the back light due to the decrease in theaperture ratios. Therefore, power consumption will be increased.

SUMMARY OF THE INVENTION

[0030] Accordingly, the present invention is directed to an IPS-LCDdevice that substantially obviates one or more of the problems due tolimitations and disadvantages of the related art.

[0031] An object of the present invention is to provide an IPS-LCDdevice having a high aperture ratio.

[0032] In order to achieve the above object, the first preferredembodiment of the present invention provides an in-plane switchingliquid crystal display device including a gate line on a firstsubstrate; a data line on the first substrate, the data line beingperpendicular to the gate line; a common line on the first substrate,the common line being parallel with the gate line and being formed of ametal; a pixel electrode and a common electrode on the first substrate,the pixel and common electrodes being formed of a transparent conductivematerial; and a liquid crystal layer between the first and secondsubstrates.

[0033] The transparent conductive material includes indium tin oxide(ITO) or indium zinc oxide (IZO).

[0034] The device further includes an auxiliary common line on the firstsubstrate, the auxiliary common line being connected with the commonelectrode. The auxiliary common line includes indium tin oxide (ITO) orindium zinc oxide (IZO).

[0035] The gate and common lines include a material selected from agroup consisting of chromium (Cr), aluminum (Al), aluminum alloy (Alalloy), molybdenum (Mo), tantalum (Ta), tungsten (W), antimony (Sb), andan alloy thereof.

[0036] The device further includes a first alignment layer on the firstsubstrate.

[0037] The first alignment layer is selected from a group consisting ofpolyimide and photo-alignment material.

[0038] The device further includes a thin film transistor at anintersection of the gate and data lines.

[0039] At least one of the pixel and common electrodes is on the samelayer with the gate electrode.

[0040] The device further includes a gate-insulating layer over thepixel electrode.

[0041] The device further includes a passivation layer over thegate-insulating layer.

[0042] The common electrode is on the passivation layer.

[0043] The device further includes a black matrix on the passivationlayer.

[0044] The black matrix includes the same material as the pixelelectrodes.

[0045] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWING

[0046] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate embodiments of theinvention and together with the description serve to explain theprinciples of the invention.

[0047] In the drawings:

[0048]FIG. 1 is a cross-sectional view illustrating a liquid crystaldisplay device according to the related art;

[0049] FIGS. 2 to 6 are perspective views illustrating operation modesof the conventional IPS-LCD device;

[0050]FIG. 7A is a plane view illustrating an array substrate of theconventional IPS-LCD device;

[0051]FIG. 7B is a cross-sectional view taken along a line “B-B” in FIG.7A;

[0052]FIG. 8 is a plane view of an array substrate of anotherconventional IPS-LCD device;

[0053]FIG. 9 is a plane view illustrating an array substrate of anIPS-LCD device according a first preferred embodiment of the presentinvention;

[0054]FIGS. 10A and 10B are different cross-sectional views fordifferent embodiments of the present invention taken along a line “X-X”of FIG. 9;

[0055]FIGS. 11A and 11B are different cross-sectional views fordifferent embodiments of the present invention taken along a line“XI-XI” of FIG. 9;

[0056]FIG. 12 is a cross-sectional view taken along a line “XII-XII” ofFIG. 9,

[0057]FIG. 13 is a plane view of an auxiliary common line;

[0058]FIG. 14 is a plane view of an auxiliary gate line;

[0059]FIG. 15 is a plane view illustrating an array substrate of anIPS-LCD device according to a second preferred embodiment of the presentinvention; and

[0060]FIG. 16 is a cross-sectional view taken along a line “XVI-XVI” ofFIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0061] Reference will now be made in detail to the preferred embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings.

[0062] First Preferred Embodiment

[0063]FIG. 9 is a plane view of an array substrate according to a firstpreferred embodiment of the present invention.

[0064] As shown in FIG. 9 and FIG. 10A, a gate line 100 is transverselydisposed on a substrate 1. A common line 120 is spaced apart from thegate line 100 and disposed parallel with the gate line 100. A data line200 that is spaced apart from each other is disposed across andperpendicular to the gate and the common lines 100 and 120.

[0065] Near an intersection of the gate and data lines 100 and 200, gateand source electrodes 110 and 210 are positioned and electricallyconnected with the gate and data lines 100 and 200, respectively. Adrain electrode 220, including a drain contact hole 240, is spaced apartfrom the source electrode 210 and overlaps a portion of the gateelectrode 110. The source electrode 210 also overlaps a portion of thegate electrode 110.

[0066] A first connecting line 320 electrically contacts the drainelectrode 220 through the drain contact hole 240, and is disposedparallel with the gate line 100. A plurality of pixel electrodes 310 aredisposed perpendicular to the first connecting line 320, and communicatewith the first connecting line 320. Ends of the pixel electrodes 310 areconnected with a second connecting line 330 over the common electrode130.

[0067] A storage electrode 230 including a storage contact hole 250 isdisposed over the common line 120, and electrically contacts the secondconnecting line 330 through the storage contact hole 250. Namely, eachof the pixel electrodes 310 is electrically connected with the storageelectrode 230.

[0068] A plurality of common electrodes 130 are disposed parallel withthe pixel electrodes 310, and electrically contact the common line 120.Each common electrode 130 is spaced apart from the adjacent pixelelectrodes 310. One end of each of the common electrodes is electricallyconnected to one another.

[0069] The common line 120 and the gate and data lines 100 and 200 arean opaque metal, while the common and pixel electrodes 130 and 310 are atransparent conductive material. Preferably, the opaque metal isselected from a group consisting of chromium (Cr), aluminum (Al),aluminum alloy (Al alloy), molybdenum (Mo), tantalum (Ta), tungsten (W),and antimony (Sb), and an alloy thereof, while the transparentconductive material is indium tin oxide (ITO) or indium zinc oxide(IZO).

[0070] Now, referring to FIG. 10A, a fabricating process for the arraysubstrate 1 shown in FIG. 9 is provided.

[0071] At first, the gate and common electrodes 110 and 130 are formedon the substrate 1. The gate line 100 of FIG. 9 is formed with the gateelectrode 110 in the same layer. Because the gate and common electrodes110 and 130 are different materials, they are formed in different steps.After that, a gate-insulating layer 132 is formed on the substrate 1 tocover the gate and common electrodes 110 and 130. Subsequently, anactive layer 134 is formed on the gate-insulating layer 132,particularly over the gate electrode 110. The gate-insulating layer 132is silicon nitride (SiNx) or silicon oxide (SiO₂), while the activelayer 134 includes an amorphous silicon layer (a-Si) and a dopedamorphous silicon layer (n⁺a-Si, not shown).

[0072] The source and drain electrodes 210 and 220 are formed on theactive layer 134, and are made of the same material as the gateelectrode 110. Further, the source and drain electrodes 210 and 220 andthe gate electrode 110 may be formed of different materials. At thispoint, the data lines 200 of FIG. 9 are formed together with the sourceelectrode 210 such that the data lines 200 and the source electrode 210are connected. Thereafter, a passivation layer 136 is deposited over thesubstrate 1 and patterned to form the drain contact hole 240 thatexposes a portion of the drain electrode 220.

[0073] Next, the pixel electrodes 310, which contact the drain electrode220 through the drain contact hole 240, are formed on the passivationlayer 136. Subsequently, though not shown in FIG. 10A, an orientationfilm of polyimide or photoalignment material is formed on the pixelelectrodes 310 and rubbed by a fabric or irradiated by light.

[0074]FIG. 10B shows a different fabricating process for the arraysubstrate 1 of FIG. 9. As shown, the pixel electrodes 310 are formed onthe gate-insulating layer 132 before the passivation layer 136 isformed. Thereafter, the passivation layer 136 is formed to cover thepixel electrodes 310.

[0075] As described above, the IPS-LCD device according to the firstpreferred embodiment of the present invention employs a transparentconductive material for the common and pixel electrodes 130 and 310 suchthat light incident from a back-light (not shown) passes through thecommon and pixel electrodes 130 and 310 with a little or no reflectionor absorption. Therefore, the aperture ratio problem of the conventionalIPS-LCD device is reduced or eliminated. For example, compared with theconventional IPS-LCD, the aperture ratio of the IPS-LCD device accordingto the first preferred embodiment increases by at least 10%.

[0076] Now, structures of other portions of the array substrate shown inFIG. 9 are described in detail with reference to FIGS. 11A, 11B, and 12.

[0077]FIGS. 11A and 11B show different structures of the common line 120and the common electrode 130.

[0078] In FIG. 11A, metal for the common line 120 is first formed on thesubstrate 1, and then the transparent conductive material is formed onthe substrate 1 to overlap a portion of the metal for the common line120. Namely, after the common line 120 is first formed on the substrate1, the common electrode 130 is later formed on the substrate 1 such thatan end of the common electrode 130 overlaps a portion of the common line120.

[0079] On the contrary, as shown in FIG. 11B, if the common electrode130 is first formed on the substrate 1, the later formed common line 120overlaps a portion of the common electrode 130. Namely, the transparentconductive material for the common electrode 130 is first formed on thesubstrate 1, and then the gate line 100 (see FIG. 9) and common lines100 and 120 are formed on the substrate 1 to overlap a portion of thecommon electrode 130.

[0080]FIG. 12 shows a storage capacitor including the storage electrode230 of FIG. 9. As shown, the common line 120 is formed together with thegate line 100 of FIG. 9 on the substrate 1. The gate-insulating layer132 is then formed to cover the common line 120. The common line 120 ismade of the same material as the gate line 100 of FIG. 9. On thegate-insulating layer 132, the storage electrode 230 is formed togetherwith the source and drain electrodes 210 and 220 of FIG. 9, and thus allof them contain the same material.

[0081] The passivation layer 136 is formed on the storage electrode 230.The storage contact hole 250 is formed in the passivation layer 136 suchthat a portion of the storage electrode 230 is exposed through a storagecontact hole 250. Thereafter, the pixel electrode 310 is formed on thepassivation layer 136 and electrically connected with the storageelectrode 230 through the storage contact hole 250.

[0082] When the common line 120 and the common electrodes 130 have thestructure shown in FIG. 11A, the common electrodes 130 preferably havethe structure of FIG. 13. As shown in FIG. 13, an auxiliary commonelectrode 125 is formed of the same transparent conductive material asthe common electrode 130 to cover the common line 120 and a common pad126. The common pad 126 is located at one end of the common line 120.The plurality of common electrodes 130 communicate with the auxiliarycommon electrode 125.

[0083] Further, as shown in FIG. 14, an auxiliary gate line 105 of thesame transparent conductive material as the common electrodes 130 ispreferably employed to cover the gate line 100 and a gate pad 106, whichis positioned at one end of the gate line 100. The auxiliary common andgate lines, respectively, protect the common and gate lines from anetching solution in later processes.

[0084] In the first preferred embodiment, since the pixel and commonelectrodes 310 and 130 in the pixel region are formed of the transparentconductive material and the gate, data, and common lines are formed ofthe metal, the aperture ratio is increased such that the brightness isimproved.

[0085] Second Preferred Embodiment

[0086] The second preferred embodiment employs an opaque metal, insteadof the ITO, for a pixel electrode. Further, in the second preferredembodiment, a black matrix is formed together with the pixel electrode.

[0087] As shown in FIGS. 15 and 16, the pixel electrodes 312 of theopaque metal are formed instead of the transparent pixel electrodes 310of FIG. 9. The black matrix 150 of opaque material is formed on thepassivation layer 136 to cover the active layer 134. To form the pixelelectrode 312 and the black matrix 150, the opaque metal layer isdeposited on the passivation layer 136 and patterned in the sameprocess. The opaque metal layer is preferably chromium (Cr), which has alow light-reflectivity.

[0088] An IPS-LCD device according to the second preferred embodiment ofthe present invention preferably employs a normally black (NB) mode LCthat displays dark when no electric field is applied to the LC.

[0089] Compared with the aperture ratio of a conventional IPS-LCD deviceemploying a black matrix that is wider than the gate or data line, theaperture ratio of an IPS-LCD device employing the array substrateaccording to the second preferred embodiment of the present inventionincreases by more than 10%.

[0090] As described above, the preferred embodiment of the presentinvention has advantages of higher aperture ratio than the conventionalone.

[0091] It will be apparent to those skilled in the art that variousmodifications and variation can be made in the method of manufacturing athin film transistor of the present invention without departing from thespirit or scope of the invention. Thus, it is intended that the presentinvention cover the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. An in-plane switching liquid crystal displaydevice comprising: a gate line on a first substrate; a data line on thefirst substrate, the data line being perpendicular to the gate line; acommon line on the first substrate, the common line being parallel withthe gate line and being formed of a metal; a pixel electrode and acommon electrode on the first substrate, the pixel and common electrodesbeing formed of a transparent conductive material; and a liquid crystallayer between the first and second substrates.
 2. The device of claim 1, wherein the transparent conductive material includes indium tin oxide(ITO).
 3. The device of claim 1 , wherein the transparent conductivematerial includes indium zinc oxide (IZO).
 4. The device of claim 1 ,further comprising an auxiliary common line on the first substrate, theauxiliary common line being connected with the common electrode.
 5. Thedevice of claim 4 , wherein the auxiliary common line includes indiumtin oxide (ITO).
 6. The device of claim 4 , wherein the auxiliary commonline includes indium zinc oxide (IZO).
 7. The device of claim 1 ,wherein the gate and common lines include a material selected from agroup consisting of chromium (Cr), aluminum (Al), aluminum alloy (Alalloy), molybdenum (Mo), tantalum (Ta), tungsten (W), antimony (Sb), andan alloy thereof.
 8. The device of claim 1 , further comprising a firstalignment layer on the first substrate.
 9. The device of claim 1 ,wherein the first alignment layer is selected from a group consisting ofpolyimide and photo-alignment material.
 10. The device of claim 1 ,further comprising a thin film transistor at an intersection of the gateand data lines.
 11. The device of claim 5 , wherein at least one of thepixel and common electrodes is on the same layer with the gateelectrode.
 12. The device of claim 1 , further comprising agate-insulating layer over the pixel electrode.
 13. The device of claim12 , further comprising a passivation layer over the gate-insulatinglayer.
 14. The device of claim 13 , wherein the common electrode is onthe passivation layer.
 15. The device of claim 13 , further comprising ablack matrix on the passivation layer.
 16. The device of claim 15 ,wherein the black matrix includes the same material as the pixelelectrodes.
 17. An in-plane switching Liquid Crystal Display (LCD)device, comprising: a first substrate and a second substrate a gate lineon the first substrate; a metal common line on the first substrate, thecommon line parallel to the gate line. a data line on the firstsubstrate, the data line being perpendicular to the gate line; a commonelectrode on the first substrate; a thin film transistor having a gateelectrode, a source electrode and a drain electrode formed on the firstsubstrate; liquid crystal interposed between the first and secondsubstrates; a pixel electrode contacting the drain electrode of the thinfilm transistor; and wherein, the pixel and common electrodes are formedof a transparent conductive material.
 18. The LCD device of claim 17 ,wherein a portion of the common line overlies a portion of the commonelectrode.
 19. The LCD device of claim 17 , wherein a portion of thecommon electrode overlies a portion of the common line.
 20. The LCDdevice of claim 17 , further comprising storage electrode.
 21. The LCDdevice of claim 20 , wherein the storage electrode contacts the pixelelectrode through a storage contact hole.
 22. The LCD device of claim 20, wherein the storage electrode is between the pixel electrode and thefirst substrate.
 23. The LCD device of claim 17 , further comprising anauxiliary common electrode covering the common line, wherein the commonelectrode is electrically connected to the auxiliary common electrode.24. The LCD device of claim 23 , wherein the auxiliary common electrodeis formed of the same transparent material as the common electrode. 25.The device of claim 23 , wherein the auxiliary common electrode includesindium tin oxide (ITO).
 26. The device of claim 23 , wherein theauxiliary common line includes indium zinc oxide (IZO).
 27. The LCDdevice of claim 23 , further comprising a common pad at an end of thecommon line.
 28. The LCD device of claim 17 , further comprising anauxiliary gate line and a gate pad covering the gate line and the gatepad.
 29. The LCD device of claim 28 , wherein the auxiliary gate line isformed of the same transparent conductive material as the commonelectrode.
 30. The device of claim 28 , wherein the auxiliary gate lineincludes indium tin oxide (ITO).
 31. The device of claim 28 , whereinthe auxiliary gate line includes indium zinc oxide (IZO).
 32. The LCDdevice of claim 17 , further comprising a black matrix on the secondsubstrate.
 33. The LCD device of claim 17 , wherein the transparentconductive material includes indium tin oxide (ITO).
 34. The LCD deviceof claim 17 , wherein the transparent conductive material includesindium zinc oxide (IZO).
 35. An in-plane switching Liquid CrystalDisplay (LCD) device, comprising: a first substrate and a secondsubstrate a gate line on the first substrate; a metal common line on thefirst substrate, the common line parallel to the gate line. a data lineon the first substrate, the data line being perpendicular to the gateline; a common electrode formed of a transparent conductive material onthe first substrate; a thin film transistor having a gate electrode, asource electrode and a drain electrode formed on the first substrate;liquid crystal interposed between the first and second substrates; and apixel electrode formed of an opaque metal contacting the drain electrodeof the thin film transistor.
 36. The LCD device of claim 35 , furthercomprising a black matrix formed of the same opaque metal as the pixelelectrode.
 37. The LCD device of claim 36 , wherein the opaque metal isCr.
 39. The LCD device of claim 35 , wherein the opaque metal is Cr.